Data stored on a computer system is typically arranged into one or more data storage spaces. Collectively, these data storage spaces are often referred to as a database. Each data storage space comprises one or more data items. Data items in a particular space share common characteristics. A data item may have a value for each of these characteristics. For example, relational databases store data in a number of spaces known as tables. The data items in each table, forming the “rows” of the table, share the same “columns” of data, in that for each column of data, any item in the table may have a value.
It is helpful to partition data storage spaces for administrative purposes such as archiving, caching, enhancing performance, copying or deleting data, and free space management. For example, spaces that store data items with date characteristics are often partitioned so that each partition comprises only those items that pertain to a particular range of dates. One partition, for example, might only store data items pertaining to a particular month. Another partition might only store data items that pertain to a particular fiscal quarter. Since a partition also comprises data items that share common characteristics, a partition may also be considered a data storage space.
The determination of to which, if any, partition a data item pertains is made by looking up one or more of the data item's values in a partition mapping. The partition mapping maps certain sets or ranges of values to certain partitions. These sets or ranges of values correspond to one or more characteristics shared by the data items in the partitioned storage space. These characteristics are known as partitioning characteristics. For tables, these sets or ranges of values may correspond to the value of a particular column upon which the partition mapping is said to be based. This column is known as the partitioning column. For example, a partition mapping for a table might be based upon the value of a data item's date column. The mapping could define ranges of dates, such as months or years. Each range could pertain to a separate partition. To determine the partition to which a new data item pertains, one would determine under which of the defined ranges the value of the item's date column fell. Partition mappings may be based on multiple partitioning columns, which is often the case with subpartitions. Partition mappings may also be based on a variety of other characteristics, such as whether a data item pertains to a particular range of numbers or set of discrete values.
It is often useful to reference a particular partition in order to perform operations with relation to the particular partition. For example, database administrators often drop partitions using a DDL statement such as the one below:                ALTER TABLE tablename DROP PARTITION partitionname;        
It is useful to reference a particular partition for a variety of other operations known within the art, such as modifying, splitting, or joining the partition.
Existing techniques for referencing a partition are problematic in that they require knowledge of the partition's name. For example, in the ALTER TABLE statement above, it was necessary to know that the partition was named partitionname. A partition's name is often unknown for a number of reasons. First of all, the partition may have been created by a person other than the person seeking to perform an operation on the partition. Second, the person who created the partition may have forgotten the partition's name. Third, partitions are often automatically assigned a name by the database system instead of by a person. This automatic assignment makes a partition's name difficult to predict.
According to existing techniques, this problem is overcome by querying the database system for a partition's name prior to referencing the partition in desired operation. This workaround is inefficient, especially when developing scripts or applications that automatically manage the partitions in the database.
A method of referencing a partition in a request to perform an operation with respect to that partition that does not rely on knowing the partition's name is therefore desirable.
The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.